This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:                3GPP third generation partnership project        ACK acknowledge (positive acknowledge)        ARI ACK/NACK resource indicator        BTS base transceiver system        BW bandwidth        CA carrier aggregation        CC component carrier        C-Plane control plane        CN core network        CQI channel quality indicator        DC dual carrier        DL downlink (eNB, Node B towards UE)        DTX discontinuous transmission        eNB EUTRAN Node B (evolved Node B)        EPC evolved packet core        EUTRAN evolved UTRAN (LTE)        GGSN gateway general packet radio system support node        GSM global system for mobile communication        HARQ hybrid automatic repeat request        HS-DSCH high speed downlink shared channel        HS-SCCH high speed shared control channel        HSPA high speed packet access        HSDPA high speed downlink packet access        HSUPA high speed uplink packet access        I-HSPA internet HSPA (evolved HSPA)        IP internet protocol        LTE long term evolution        MAC medium access control        MIMO multiple input, multiple output        MM/MME mobility management/mobility management entity        NACK not acknowledge/negative acknowledge        NBAP Node B application part (signaling)        Node B base station (includes BTS)        OFDMA orthogonal frequency division multiple access        O&M operations and maintenance        Pcell primary cell        PDCP packet data convergence protocol        PDU protocol data unit        Phy physical        PMI pre-coding matrix index        PRB physical resource block        PDCCH physical downlink control channel        PDSCH physical downlink shared channel        PUCCH physical uplink control channel        PUSCH physical uplink shared channel        RACH random access channel        RAN radio access network        RAT radio access technology        RB radio bearer        RE resource element        RF radio frequency        RLC radio link control        RNC radio network controller        ROHC robust (internet) header compression        RRC radio resource control        SAW stop-and-wait        Scell secondary cell        SC-FDMA single carrier, frequency division multiple access        SGSN serving gateway support node        SGW serving gateway        SIMO single input, multiple output        SINR signal to interference plus noise ratio        SR scheduling request        TCP transmission control protocol        TFRC TCP-friendly rate control        TTI transmit time interval        U-Plane user plane        UE user equipment        UL uplink (UE towards eNB, Node B)        UTRAN universal terrestrial radio access network        WCDMA wideband code division multiple access        
The specification of a communication system known as evolved UTRAN (EUTRAN, also referred to as UTRAN-LTE or as EUTRA) has been specified by 3GPP in Rel-8 (release eight). As specified the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.10.0 (2009-9), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8). This system may be referred to for convenience as LTE Rel-8 (which also contains 3G HSPA and its improvements). In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LTE system. More recently, Release 9 and Release 10 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.1.0 (2009-9).
FIG. 1 reproduces FIG. 4-1 of 3GPP TS 36.300, and shows the overall architecture of the E-UTRAN system. The E-UTRAN system includes eNBs, providing the EUTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity) by means of a S1 MME interface and to a Serving Gateway (SGW) by means of a S1 interface. The S1 interface supports a many to many relationship between MMEs/Serving Gateways and eNBs.
Reference can be made to 3GPP TR 36.814, V1.2.1 (2009-06), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Further Advancements for E-UTRA Physical Layer Aspects (Release 9). Reference can also be made to 3GPP TR 36.913, V8.0.1 (2009-03), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release 8). A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost.
GSM, WCDMA, and LTE in their first releases utilized single carrier transmission. Since then, multicarrier operation has been introduced in GERAN EGDE and WCDMA HSDPA (TS25.308 Rel-8, Rel-9) and HSUPA in (TS25.319 Rel9) operation. In HSPA multicarrier operation, the UE and Node B transmit on two parallel carriers in quite an independent manner and the multicarrier operation can be seen as multiple parallel single carrier transmissions performed on different carrier frequencies to/from the single UE. The multicarrier operation in HSDPA (dual cell or dual band) supports only single carrier uplink operation, but the dual carrier HSUPA requires dual carrier uplink operation.
As is specified in 3GPP TR 36.913, LTE-A should operate in spectrum allocations of different sizes, including wider spectrum allocations than those of Rel-8 LTE, e.g., up to 100 MHz, to achieve the peak data rate of 100 mega-bits per second (Mbit/s) for high mobility and 1 Gbit/s for low mobility. LTE-A (to be included into 3GPP Release-10) is going to include carrier aggregation (CA), providing the capability to aggregate together up to five LTE carriers referred to as Component Carriers (CCs). Rel-8 terminals receive/transmit on one component carrier, whereas LTE-Advanced terminals may receive/transmit on multiple component carriers simultaneously to achieve higher (e.g., wider) bandwidths.
While there are benefits to these scenarios, there are additional improvements that could be made.